// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_PROXY_PROXY_SCRIPT_FETCHER_IMPL_H_
#define NET_PROXY_PROXY_SCRIPT_FETCHER_IMPL_H_

#include <stddef.h>

#include <memory>
#include <string>

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/strings/string16.h"
#include "base/time/time.h"
#include "net/proxy/proxy_script_fetcher.h"
#include "net/url_request/url_request.h"

class GURL;

namespace net {

class URLRequestContext;

// Implementation of ProxyScriptFetcher that downloads scripts using the
// specified request context.
class NET_EXPORT ProxyScriptFetcherImpl : public ProxyScriptFetcher,
                                          public URLRequest::Delegate {
public:
    // Creates a ProxyScriptFetcher that issues requests through
    // |url_request_context|. |url_request_context| must remain valid for the
    // lifetime of ProxyScriptFetcherImpl.
    // Note that while a request is in progress, we will be holding a reference
    // to |url_request_context|. Be careful not to create cycles between the
    // fetcher and the context; you can break such cycles by calling Cancel().
    explicit ProxyScriptFetcherImpl(URLRequestContext* url_request_context);

    ~ProxyScriptFetcherImpl() override;

    // Used by unit-tests to modify the default limits.
    base::TimeDelta SetTimeoutConstraint(base::TimeDelta timeout);
    size_t SetSizeConstraint(size_t size_bytes);

    void OnResponseCompleted(URLRequest* request);

    // ProxyScriptFetcher methods:
    int Fetch(const GURL& url,
        base::string16* text,
        const CompletionCallback& callback) override;
    void Cancel() override;
    URLRequestContext* GetRequestContext() const override;

    // URLRequest::Delegate methods:
    void OnAuthRequired(URLRequest* request,
        AuthChallengeInfo* auth_info) override;
    void OnSSLCertificateError(URLRequest* request,
        const SSLInfo& ssl_info,
        bool is_hsts_ok) override;
    void OnResponseStarted(URLRequest* request) override;
    void OnReadCompleted(URLRequest* request, int num_bytes) override;

private:
    enum { kBufSize = 4096 };

    // Read more bytes from the response.
    void ReadBody(URLRequest* request);

    // Handles a response from Read(). Returns true if we should continue trying
    // to read. |num_bytes| is 0 for EOF, and < 0 on errors.
    bool ConsumeBytesRead(URLRequest* request, int num_bytes);

    // Called once the request has completed to notify the caller of
    // |response_code_| and |response_text_|.
    void FetchCompleted();

    // Clear out the state for the current request.
    void ResetCurRequestState();

    // Callback for time-out task of request with id |id|.
    void OnTimeout(int id);

    // The context used for making network requests.
    URLRequestContext* const url_request_context_;

    // Buffer that URLRequest writes into.
    scoped_refptr<IOBuffer> buf_;

    // The next ID to use for |cur_request_| (monotonically increasing).
    int next_id_;

    // The current (in progress) request, or NULL.
    std::unique_ptr<URLRequest> cur_request_;

    // State for current request (only valid when |cur_request_| is not NULL):

    // Unique ID for the current request.
    int cur_request_id_;

    // Callback to invoke on completion of the fetch.
    CompletionCallback callback_;

    // Holds the error condition that was hit on the current request, or OK.
    int result_code_;

    // Holds the bytes read so far. Will not exceed |max_response_bytes|.
    std::string bytes_read_so_far_;

    // This buffer is owned by the owner of |callback|, and will be filled with
    // UTF16 response on completion.
    base::string16* result_text_;

    // The maximum number of bytes to allow in responses.
    size_t max_response_bytes_;

    // The maximum amount of time to wait for download to complete.
    base::TimeDelta max_duration_;

    // The time that the fetch started.
    base::TimeTicks fetch_start_time_;

    // The time that the first byte was received.
    base::TimeTicks fetch_time_to_first_byte_;

    // Factory for creating the time-out task. This takes care of revoking
    // outstanding tasks when |this| is deleted.
    base::WeakPtrFactory<ProxyScriptFetcherImpl> weak_factory_;

    DISALLOW_COPY_AND_ASSIGN(ProxyScriptFetcherImpl);
};

} // namespace net

#endif // NET_PROXY_PROXY_SCRIPT_FETCHER_IMPL_H_
